When backing up material hauling vehicles such as semitrailers and others types of trucks used for transporting goods to a loading dock, because of the long length of the truck there is a danger that the rear end of the truck will hit, and possibly damage the loading dock. The truck may also be damaged Typically, a driver of a semi-trailer truck, for example, will attempt to determine how close the back-end of his truck is to the loading dock as he backs toward the loading dock. Because of the distances and depth perception problems involved, it is very difficult for the driver to accurately judge how close the back end of his truck is to the loading dock. Consequently, additional personnel will be required to assist the driver in backing up to the loading dock.